A fuel cell is a cell which utilizes the opposite principle to the electrolysis of water to obtain electricity in the process of obtaining water by causing a reaction between hydrogen and oxygen. Because generally a fuel gas is substituted for hydrogen and air or an oxidant gas is substituted for oxygen, the terms fuel gas, air and oxidant gas are often used.
As this kind of fuel cell, for example the “fuel cell” in JP-A-2000-123848 is known. The cell of this fuel cell is constructed as shown in FIG. 11.
As shown in FIG. 11, a cell 100 is made by affixing an anode side electrode 102 and a cathode side electrode 103 to both sides of an electrolyte membrane 101 and sandwiching the anode side electrode 102 and the cathode side electrode 103 with two separators 104, 105. Multiple flow grooves 106 for supplying hydrogen gas, which is a fuel, to the anode side electrode 102 are formed in the separator 104, and multiple flow grooves 107 for supplying oxygen gas, which is an oxidant gas, to the cathode side electrode 103 are formed in the separator 105. A required voltage is obtained by stacking numerous cells 100 constructed like this.
The reference numerals 111, 112 denote seals (gaskets) for sealing the gaps between the electrolyte membrane 101 and the separators 104, 105.
The electrolyte membrane 101 is a polymer electrolyte membrane (PEM: Polymer Electrolyte Membrane) made of a polymer compound. This electrolyte membrane 101 will hereinafter be written PEM 101.
And, the PEM 101, the anode side electrode 102 and the cathode side electrode 103 constitute a membrane/electrode assembly (MEA: Membrane Electrode Assembly) 108. This membrane/electrode assembly 108 will hereinafter be written MEA 108.
In the above-mentioned Japanese patent publication there is no description of a manufacturing method and a carrying method of the MEA 108, but generally a method is known wherein [1] to the front and rear sides of a PEM cut larger than the shape to which it is to be finally shaped an anode side electrode 102 and a cathode side electrode 103 with a smaller area than this PEM are press-affixed; [2] the edge of the PEM is finally shaped by cutting (trimming) with a trimming blade; and [3] the trimmed membrane-form MEA 108 is suction-gripped with a suction-gripping device while being carried to the next step.
The present inventors tried this manufacturing and carrying, but in the trimming (final shaping) step [2] and the carrying step [3] the kinds of problem shown in FIG. 12A to FIG. 12C arose.
FIG. 12A to FIG. 12C are explanatory views illustrating an MEA trimming step and a carrying step which follows this trimming step: FIG. 12A is a sectional view showing the trimming process; FIG. 12B is a sectional view showing a suction-gripping operation; and FIG. 12C is a sectional view showing a carrying operation.
In FIG. 12A, with a PEM 101a with electrodes 102, 103 affixed to it placed on a table 121 and positioned by positioning means not shown in the figure, a press apparatus 123 fitted with a trimming blade 122 is lowered as shown by the white arrow and the PEM 101a is trimmed. To distinguish it from the post-trimming PEM 101, the pre-trimming PEM is denoted with the reference numeral 101a. 
In FIG. 12B, after trimming of the PEM 101 is finished, a suction-gripping apparatus 124 separate from the press apparatus 123 (see FIG. 12A) is lowered as shown by the white arrow and suction-grips the MEA 108.
In FIG. 12C, the MEA 108 suction-gripped by the suction-gripping apparatus 124 is lifted as shown by the white arrow d and carried to a subsequent stacking step as shown by the white arrow e.
In FIG. 12B, because the press apparatus 123 shown in FIG. 12A and the suction-gripping apparatus 124 shown in FIG. 12B are interchanged on the table 121 before the suction-gripping operation is carried out, the flow temporarily stops at the time of the transition from the trimming process to the suction-gripping process. Consequently, when trimming and carrying of the MEA 108 are carried out continuously on a production line, productivity can be expected to fall greatly.
The MEA 108, having had its edges trimmed to a predetermined size, after this edge-trimming, is carried from a trimming station, where the edge-trimming is carried out, to a stacking station, to be stacked with a separator. In FIG. 12A and FIG. 12B, from when the PEM 101a is trimmed by the press apparatus 123 to when it is suction-gripped by the suction-gripping apparatus 124, for example, if the position of the MEA 108 slips, the MEA 108 is carried by the suction-gripping apparatus 124 with its position still slipped, and in the stacking step, the position of the MEA 108 must be corrected. As a result, the manufacturing labor of the fuel cell may increase and the productivity of the fuel cell may fall.
Also, a separate problem of the kind shown in FIG. 13A and FIG. 13B arose.
FIG. 13A and FIG. 13B are explanatory views illustrating an MEA trimming apparatus and trimming process: FIG. 13A is a sectional view showing before the trimming process, and FIG. 13B is a sectional view showing after the trimming process.
In FIG. 13A, first, a PEM 101a (to distinguish it from the post-trimming PEM 101, the reference numeral of the pre-trimming PEM will for convenience be made 101a) with electrodes 102, 103 affixed to its sides is placed on a table 131, and the edges of the PEM 101a are fixed to the table 131 with for example clamping members 132.
Then, from above the PEM 101a , a press apparatus 123 fitted with a trimming blade 122 is lowered as shown with arrows, and the PEM 101a is trimmed by the trimming blade 122.
When the above-mentioned clamping members 132 are used to fix the PEM 101a, when the clamping members 132 are tightened, it sometimes happens that a clamping member 132 moves and makes a crease in the PEM 101a, which is a film-like workpiece, or that clamping members 132 pull on the PEM 101a against each other and stretch the PEM 101a, and the quality of the PEM 101a is impaired.
And, also when the PEM 101a is positioned on the table 131, because it is a film-like workpiece, a method must be used such that it is not damaged.
Also, when metal ions attach to the electrodes 102, 103, these metal ions bond with electrons and metal separates at the carbon electrode. It sometimes happens that because of this, separated metal hinders the reaction between the hydrogen and the oxygen and lowers the performance of the fuel cell, and to improve the performance of the fuel cell it is desirable for the attachment of metal ions to the electrodes 102, 103 to be prevented.
In FIG. 13B, when trimming is finished, the press apparatus 123 is raised as shown with arrows.
It sometimes happens that the MEA 108 made up of the PEM 101 and the electrodes 102, 103, of which trimming is finished, has slipped sideways as shown with a white arrow, and if sideways slipping occurs before trimming is completed, the accuracy of the trimming becomes poor and the quality of the fuel cell is impaired.
Also, the kinds of problem shown in FIG. 14A, FIG. 14B, FIG. 15A and FIG. 15B occurred.
FIG. 14A and FIG. 14B are explanatory views illustrating an MEA trimming apparatus and a trimming blade shape, which has an influence on the trimming process of this trimming apparatus: FIG. 14A is a sectional view showing before the trimming process and FIG. 14B is a sectional view showing trimming in progress.
In FIG. 14A, a PEM 101a having electrodes affixed to its sides is placed on a table 131. Next, from above the PEM 101a, a trimming blade 122 in the blade edge 122a of which undulations have arisen is lowered as shown with a white arrow. (For the purposes of illustration, the degree of undulation in the blade edge 122a has been exaggerated.)
In FIG. 14B, the PEM 101a is trimmed with the trimming blade 122. However, because of the undulations in the blade edge 122a, of the cross-section of the PEM 101a, the parts shown with cross-hatching are not trimmed.
To trim the PEM 101a completely, the trimming blade 122 must be pushed against the PEM 101a with a still larger pushing force, and because the load acting on the trimming blade 122 becomes large, it is necessary to increase the strength of the trimming blade 122 to withstand this load and to make the cylinder apparatus for pushing the trimming blade 122 large.
FIG. 15A and FIG. 15B are explanatory views illustrating an MEA trimming apparatus and a trimming blade inclination, which has an influence on the trimming process of this trimming apparatus: FIG. 15A is a sectional view showing before the trimming process, and FIG. 15B is a sectional view showing trimming in progress.
In FIG. 15A, a PEM 101 with electrodes affixed to its sides is placed on a table 131.
From above the PEM 101a a trimming blade 135 is lowered as shown with a white arrow.
For example, when the parallelness of the upper face of the table 131 and the blade edge 136 of the trimming blade 135 is large (the blade edge 136 is inclined at an angle θ to the upper face of the table 131), in FIG. 15B, when the PEM 101a is trimmed with the trimming blade 135, of the cross-section of the PEM 101a , the part shown with cross-hatching is not trimmed.
Consequently, to trim the PEM 101a, in the same way as that explained with reference to FIG. 14A and FIG. 14B, it is necessary to apply a still larger pushing force to the trimming blade 135.